1. Field of the Invention
The invention relates to semiconductor technology and more particularly to a light sensing device.
2. Description of the Related Art
In WO 2004/027880 A2, a spacer wafer between two lens wafers to maintain a gap therebetween is disclosed. It is critical to align the substrates because alignment errors therebetween may negatively affect the optical performance of the final light sensing device.
The lenses on the lens wafers are typically formed of transparent polymer cured by illumination of ultraviolet (UV) light or heating. The lens substrates are usually deformed and thus have serious warpage during the lens replication process or substrate bonding process. The spacer and lens substrates typically comprise alignment marks at either side thereof. Due to warpage of the substrates, even if the alignment marks are accurately aligned, and then the substrates are bonded, the corresponding lenses and the spacers of the substrate cannot be accurately aligned.